The project contains a shader "Custom/HalfTextureColor" that contains the following:
```
struct Varyings
{
min16float4 positionCS : SV_POSITION;
min16float2 uv : TEXCOORD0;
};
```
According to the HLSL documentation, `SV_POSITION` must be declared as `float4`. Also, according to Metal Shading Language documentation, section 5.2.3.3, the vertex shader ouput position must also be `float4`. The Metal shader compiler will output errors otherwise. Therefore, Unity displays the mentioned warning "SV_Position must be a 4-component 32-bit float vector or a composite which recursively contains only such a vector at line 44".
In addition, if the shader accesses high resolution textures (with either width or height bigger than 2048), it might be worth considering changing the type of `uv` to `float4`, as 16-bit floats start to have precision problems with values higher than 2048. For example, 16-bit floats don't have enough precision to represent the number 2049.